1. Technical Field
The present disclosure relates to in vivo systems and methods of identifying tissue parameters (e.g., tissue type) and assessing the conditions of the tissue during a surgical procedure. More specifically, the present disclosure relates to systems and methods for measuring the relative level of blood circulation in tissue with an energy-based surgical instrument for vessel sealing.
2. Background of Related Art
Correctly identifying tissue parameters including tissue type is important for any surgical operation. But it is especially important during laparoscopic operations when a surgeon can only view tissue through a camera. A camera, however, may provide a surgeon with a limited view of the tissue. As a result, several ex vivo and in vivo methods have been proposed to measure different characteristics of tissue in order to identify and assess the tissue.
Publication number US 2008/0200843 describes a method and apparatus for measuring human tissue properties in vivo. The method is based on sensing the mechanical response of tissue. The method includes applying a predetermined force to the surface of a patient with a probe and measuring the displacement of the probe as a function of applied force. Tissue properties are then determined based on the result of measuring the displacement of the probe.
Publication number US 2008/0154145 describes a method and apparatus for determining characteristics of biological tissues. Tissue characteristics are determined by introducing a sound wave into the tissue and recording the response of the tissue to the sound wave.
Publication number US 2009/0124902 describes a method for classifying tissue from the lumbar region using a combination of ultrasonic and optical measurements.
In publication number US 2007/0276286, a miniature electrode array is used to stimulate tissue and to measure a tissue response in order to provide tissue diagnosis and spatial tissue mapping.
Publication number US 2005/0283091 describes a method and apparatus for determining the conditions of biological tissue. The method includes exciting tissue with electrical signals at different frequencies and analyzing the cross-correlation of response signals with delayed excitation signals. Cross-correlation products are then auto-correlated. Cross-correlation products correspond to tissue conditions and auto-correlation products correspond to changes in the tissue conditions.
Publication number US 2003/0060696 discloses an apparatus for recognizing tissue type using multiple measurement techniques. For example, electrical signals are applied to a tissue via electrodes to measure impedance magnitude and phase at a plurality of frequencies. The phase information at the plurality of frequencies is compared with the phase information of known tissue types to identify the tissue type.
Publication number US 2002/0077627 describes a method for detecting and treating tumors using localized impedance measurements. The method includes providing an impedance measurement apparatus having a plurality of resilient members deployable to sample tissue impedance through a plurality of conductive pathways. Information from the impedance measurements is then used to determine the condition of the tissue.
Publication number US 2009/0253193 describes a device for characterizing tissue ex vivo. The device includes a set of independent electrodes that scan the tissue by moving a voltage gradient across the tissue surface and acquiring impedance spectrographs that may be mapped to an image.
U.S. Pat. No. 5,769,791 describes a tool for nondestructive interrogation of the tissue including a light source emitter and detector, which may be mounted directly on the surgical tool in a tissue contacting surface or mounted remotely and guided to the surgical field with fiber optic cables.
Publication number US 2009/0054908 describes a system having a surgical instrument with a sensor for generating a signal indicative of a property of a patient's tissue. The signal is converted into a current dataset and stored. A processor compares the current dataset with other previously stored datasets and uses the comparison to assess a physical condition of the tissue and/or to guide a procedure being performed on the tissue.
Although existing methods can provide various measurements of tissue parameters, these methods may be difficult to implement because of their complexity and may provide inaccurate measurements.